c5 parking break
you have to pull the rotor and the adjuster is on the bottom of the backing plate.
I adjust mine so that the parking brake holds when the handle is at 5 clicks. Do one side at a time until 5 clicks hold the rotor, then do the other side until 5 clicks hods that side and then put it all back together.
for some reason I have to adjust mine about once every 4 months or so.


